1. FIELD OF THE INVENTION
The present invention relates to an electronic musical instrument comprising a keyboard.
2. DESCRIPTION OF THE BACKGROUND
In some electronic musical instruments having keyboards, a duet tone (ensemble tone) is generated in correspondence with a specific melody tone played at a keyboard, and is added to the melody tone, thus performing an auto-play operation.
A conventional electronic musical instrument, which automatically adds a duet tone to a melody tone played at a keyboard, discriminates the tonality, flow, and the like of a music piece to be played, and faithfully adds a duet tone according to the music theory. In this duet tone generation method, however, a player must designate a tonality in advance, and a play error cannot be coped with.
As an improved electronic musical instrument, with which a beginner can easily enjoy a duet tone play operation, which adds a duet tone as follows, is known. More specifically, the type of chord and the root note of the chord are detected in advance on the basis of a depressed key. When a player plays a melody, depressed keys of the melody tones are detected, and an interval between each detected melody tone and the root note of the chord, i.e., an interval of each melody tone with respect to the root is obtained as semitone count data, and difference data of a duet tone to be added is obtained from a table according to the semitone count data obtained in this manner, i.e., relative note data R.multidot.N, and the type of chord. More specifically, difference data representing an interval (difference) between a duet tone to be added and a melody tone as semitone count data are stored beforehand in a table according to an interval (relative note data R.multidot.N) of a melody tone with respect to a root note in units of types of chords such as major chords, minor chords, seventh chords, and the like, and the difference data of a duet tone is obtained from the table according to the detected chord and the relative note data R.multidot.N. The pitch of the duet tone to be added is determined on the basis of the obtained difference data, and the root note of the chord, thus generating the duet tone.
According to this apparatus, when a player plays a melody, a duet tone can be added on the basis of the difference data read out from the table, thus easily obtaining the duet tone. However, since the difference data of duet tones are stored according to the types of chords and relative note data R.multidot.N, a development table for storing difference data of duet tones corresponding in number to the product of the number of chords and the number of relative note data R.multidot.N is required. As a result, the capacity of the memory for storing data for obtaining a duet tone to be added is undesirably increased.